The Epic battery series, currently more than $55,000 past its modest $1,000 Kickstarter goal, are add-on batteries similar to GoPro's BacPac batteries, but with longer life -- up to 8 hours of continuous use.

For GoPro Hero 3/3+ owners, the Epic L52G3 is a 5,200mAh battery that's designed to fit into and extend from the battery cavity on the back of the camera. You'll remove the standard battery pack and simply slide the Limefuel pack in.

The battery is nearly the same size as the camera and weighs 110 grams (3.9 ounces), making the camera with battery about 153 grams (5.4 ounces). To handle the extra bulk, Limefuel includes two waterproof housing backs: one good down to 40 meters (131 feet) and another down to 60 meters (197 feet).

The Hero4 battery pack, Epic L38G4, was originally designed as a two-piece battery to deal with that camera's bottom-loading battery compartment. One piece would go into the battery compartment while a second battery attached to the back of the camera with a thin ribbon cable connecting the two.

However, after surveying its backers, the overwhelming response was for a single pack similar GoPro's BacPac battery design.

Limefuel didn't leave out users of GoPro's entry-level Hero camera, either. The Epic L40GH boosts that model's internal battery for up to 8 hours of recording, too, and comes with the 40-meter backdoor.

Prices for the batteries through the Kickstarter start at $35 (about £25 and AU$45), but there are several packages available depending on how much you want to pledge. Even if you just want some extra batteries, Limefuel has them for a $1 pledge plus shipping.